OK, something is weird

I have found several online sites for looking for jobs in my career. Mind you, I found these months ago but did not find them a couple of years ago when I was looking for a job in this same field. Anyway, these sites make you register and oddly enough, I keep getting spam from them in the guise of "they have new listings- come back to their site". But, it is always the same job description- just listed like the opening just got listed. This is a free site and they aren't getting anything from me. I can't believe that with the economy so bad and no jobs for people around here in my field that the same companies are having to list the same job opening month after month- like they can't fill it. And it would be very coincidental for more than one company to list the exact wording for a job opening. Also, I haven't gotten the first call thru these resumes I've sent thru this site.

So- if this is a scam like it appears to be- exactly what are these people getting out of this?

I figured out that all one site does is list employers that they got another, legitimate site. Maybe they are just doing all this to make companies think they are a viable option for listing job openings- that they can get potential employees to respond.

And there's another one- Yahoo - that used to be legotimate but now is over-run by ads for "work from home" or "surveyors needed" by the same poster and you have to look thru at least a hundred of these to get to one REAL job listing.